1. Field of the Invention
The invention relates to process equipment for refining high-molecular-weight compounds, namely to apparatus for a thermal decomposition of polymeric materials. The invention may prove most advantageous in chemical, petrochemical and petroleum refining industries when utilizing such materials as vulcanized and nonvulcanized rubbers, polyethylene, polystyrene, polypropylene etc.
2. Description of the Prior Art
Oil deficiency has recently provoked a need to search for other sources of raw materials for producing products originally obtained from oil.
Due to this fact, research workers have paid special attention to utilization and refining of waste polymeric materials, the annual amount of such wastes being more than 10 million tons. Up to now, the problem of expanding the range of upgrading the quality of products obtainable by refining waste polymeric materials, has preserved its urgency. A solution of this problem depends to a great extent on the design of the equipment utilized in refining polymeric materials.
Known in the art is an apparatus for refining polymeric materials, comprising a reactor, a mixing chamber, and a heater (USSR Inventor's Certificate No. 137,441). This apparatus is used essentially for producing bitumen from asphaltic bitumen, and is practically unsuitable for refining such polymeric materials as rubbers, polyethylene and the like.
Also known in the art is an apparatus for a thermal decomposition of polymeric materials, possessing wider processing possibilities (Lyakhevich G. D. et al., Issledovaniya protsessa termokhimicheskoy pererabotki uglei i nefteproduktov, "Izvestiya Akademii nauk Belorusskoi SSR", seriya khimicheskikh nauk, 1974, No. 3, pp. 88-90).
The above apparatus comprises a reaction chamber provided with a charging hole, a branch pipe for discharging a suspension, and with a branch pipe for withdrawing a vapour-gas phase, the latter being communicated with a condenser. The reaction chamber is constructed in the form of a vertical cylinder and is mounted within a heater in the form of an electric furnace. Within the reaction chamber there is installed a vertical shaft provided with blades, said shaft being connected with a rotation drive.
In the process of refining polymeric materials, finely divided raw material is charged into the chamber through the above-mentioned charging hole. A solvent is poured through the same hole and after charging and mixing are over, the heater is switched on. If such a sequence of operations is not observed, the reaction mass will inevitably coke and sinter. Therefore, the apparatus cannot operate in the continuous mode, which combined with a low process rate, adversely effects its efficiency. The range of products obtained in the apparatus is limited due to the fact that the processes of a thermal decomposition of a starting raw material and distillation for the separation of the end products are carried out practically within a single volume, i.e. reaction chamber. It is obvious that such an arrangement does not provide the possibility of selecting optimum conditions for the given processes. As a result, the quality of obtained end products is often unsatisfactory.
It should be also noted that with the given design of the apparatus, the attempt to expand the range of the obtained end products by means of increasing the distillation temperature or by increasing the duration of this operation is useless since it inevitably results in coking the reaction mass, choking and increased wear of the equipment.